The present inventive concept relates to camera modules and methods of fabricating the same, and more particularly, to camera modules including housings capable of effectively shielding electromagnetic (EM) waves, and methods of fabricating the same.
FIG. 1 is an exploded perspective view of a conventional camera module, and FIG. 2 is a cross-sectional view of the assembled camera module shown in FIG. 1.
Referring to FIGS. 1 and 2, the camera module may include a lens group 10, a lens container 20, a housing 30, and an image sensor 40. The lens group 10 may include at least one lens 12 arranged in the direction of an optical axis X and be contained in the lens container 20.
The lens container 20 may be a containing member with a predetermined size. The container member may include an incidence hole 24 with a predetermined size, which is formed in the center of a front surface of the lens container 20 and has a center disposed about the optical axis X. Also, the lenses 12 of the lens group 10 may be arranged about the optical axis X. In this case, the lens container 20 may include a hollow cylindrical barrel 21 and a cap 23. The hollow cylindrical barrel 21 includes a positive screw unit 21a, which is disposed in an outer surface of the hollow cylindrical barrel 21 and helically fastened with a negative screw unit 31a formed in an assembling hole 31 of the housing 30. The lens group 10 is arranged in the body of the hollow cylindrical barrel 21 about the optical axis X. The cap 23 includes the incidence hole 24 (which is disposed in the center of the front surface of the cap 23) and is helically fastened with an inner surface of the barrel 21 to fix the lens group 10. When the cap 23 is helically fastened with the top end of the barrel 21, a projection 25 by which the lowermost end is caught may protrude from the bottom end of the barrel 21. Although FIG. 2 illustrates the cap 23 with an assembling structure helically fastened with the top end of the barrel 21, the cap 23 may have an alternative assembling structure.
The housing 30 includes a body 33 through which the assembling hole 31 is formed to contain the lens container 20 in the housing 30. The housing 30 is mounted on the top surface of a substrate 45. The assembling hole 31 may include the negative screw unit 31a helically fastened with the positive screw unit 21a formed in the barrel 21, such that the lens container 20 is assembled in the housing 30 while moving about the optical axis X. Also, the housing 30 may be mounted on the top surface of the substrate 45 with an adhesive 32, such as epoxy resin. In this case, the adhesive 32 used for fixing the housing 30 to the substrate 45 may be a conductive adhesive, such as anisotropic conductive paste (ACP) or an anisotropic conductive film (ACF).
Meanwhile, various circuit patterns may be printed on the substrate 45. The image sensor 40 may be mounted on one side of the substrate 45, while a connector (not shown) for easily connecting the camera module with other electronic components may be disposed on the other side thereof. The image sensor 40 may be a sensing member, which includes an image region 40a disposed on the top surface thereof. Light passing through the lens group 10 of the lens container 20 is irradiated to the image region 40a to form an image. The image sensor 40 is electrically connected to the substrate 45 so that the image sensor 40 may convert the formed image into an electric signal and transmit the electric signal to a display unit. The substrate 45 may be a flexible printed circuit board (FPCB) with a relatively small thickness or other ordinary PCB. As shown in FIGS. 1 and 2, when the image sensor 40 is mounted on the substrate 45, a plurality of bonding pads 47a formed on the substrate 45 may be electrically connected to a plurality of bonding pads 47b formed on the image sensor 40 by means of a wire bonding technique using metal wires 47. Also, an optical filter member 50 functioning as an infrared (IR) cut-off filter may be mounted between the lens group 10 and the image sensor 40.
The above-described conventional camera module is fabricated as separated components, such as the lenses 12, the image sensor 40, and the housing 30. Thus, downscaling the camera module is difficult and fabricating the camera module becomes increasingly expensive.
Forming a housing using a conductive material has been required more and more in order to shield electromagnetic (EM) waves. Due to the increasing usage of digital electronic components and their ever-increasing clock frequencies, EM waves may give rise to various disadvantages, such as interference between channels of a wireless communication system, thereby deteriorating the utility of spectra and the reliability of information and communication networks. Furthermore, the EM waves may greatly affect an ecosystem including the human body. In other words, more attention must be paid to the electromagnetic compatibility (EMC) of electronic components. The EMC may be classified into electromagnetic interference (EMI) and electromagnetic susceptibility (EMS). EMI refers to a phenomenon where radio-frequency (RF) energy and noise radiated from a product detrimentally affects other adjacent products. Conversely, EMS refers to a phenomenon where a product has a tolerance to all RF energy and noise radiated from other adjacent products that effect normal operations of the product. Hereinafter, the term “to shield EM waves” will carry the meaning of to minimize EMI and maximize EMS.
In order to fabricate the camera module shown in FIGS. 1 and 2, the housing 30 is formed as an independent component and combined with a package structure including the image sensor 40. In this case, the housing 30 is highly likely to be sensitive to dimensional variance such that dimensional variance may degrade an EMI-resistant characteristic of the camera module. In addition, a complicated epoxy process should be performed to combine the housing 30, which is formed of a conductive material, with the package structure including the image sensor 40.